How to Make It
Preheat oven to 350°F. Place bacon on a wire rack set in a 10- x 15-inch rimmed baking sheet lined with aluminum foil. Bake in oven until bacon is crispy, 25 to 30 minutes. Roughly chop; set aside. Reserve bacon drippings in pan; remove wire rack.
Increase oven temperature to 425°F. Cook pasta to al dente according to package directions. Drain, reserving 1/2 cup cooking water. Return hot pasta to pot. Add spinach and reserved cooking water to pasta; stir until wilted, 1 to 2 minutes. Add Alfredo sauce, tomatoes, mustard, lemon zest, and bacon; stir to combine.
Spread pasta mixture in an even layer in reserved drippings in rimmed baking sheet. Sprinkle with cheese. Bake at 425°F until it’s melted and golden brown in spots, about 15 minutes. Garnish with parsley.